Add propTypes to ItemMetadataView

src/ItemMetadataView.js

@@ -1,4 +1,5 @@
 import React from 'react';
+import PropTypes from 'prop-types'
 import { makeStyles, Grid, Paper } from '@material-ui/core';
 import { Alert } from '@material-ui/lab'
 
@@ -40,4 +41,9 @@ export default function ItemMetadataView({item}){
 			</Grid>
 		</>
 	);
-}
+}
+
+ItemV.ItemMetadataView = {
+	/** The item to be displayed. */
+	"item": PropTypes.object.isRequired
+};